A multiuser beamforming system supports multiple users by using a beamforming scheme in a multi antenna environment. The Beamforming scheme in a multi antenna environment may be largely divided into Orthogonal Multiple Access (OMA) based beamforming and Non-Orthogonal Multiple Access (NOMA) based beamforming.
OMA based beamforming (or OMA beamforming) supports a number of users that is less than the number of antennas of a transmitting end. The OMA beamforming shares space resources per user. In other words, the OMA beamforming supports only one user per beam. Accordingly, if a zero-forcing beamforming scheme is used, there is no inter-user interference. In this case, however, the number of users to be supported concurrently (e.g., the number of concurrent users) is limited by the number of antennas of the transmitting end, thus restricting the improvement of communication capacity (or sum capacity).
NOMA based beamforming (or NOMA beamforming) supports a number of users that is more than the number of antennas of the transmitting end. The NOMA beamforming generates beams more than the number of antennas of the transmitting end, thus increasing the number of concurrent users. However, because inter-beam orthogonality is not sustained, performance degradation of the communication capacity occurs, and in this regard, as the number of concurrent users increases, the performance degradation of communication capacity gets worse. Accordingly, the NOMA beamforming rather lags far behind in the communication capacity to the OMA beamforming. Therefore, a need exists for a technology to cancel or minimize inter-beam interference to overcome performance degradation of communication capacity that may occur when such a NOMA based beamforming scheme is used.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.